Cooling means for variable area nozzles



J 1952 c. R. BROWN COOLING MEANS FOR' VARIABLE AREA NOZZLES Filed Sept. 30, 1949 INVENTOR Charles R. Brown ATTORNEY Patented July 15, 1952 CUOLIN G MEANS FOR VARIABLE AREA NOZZLES Charles R. Brown, Glen Mills, Pa., assignorto Westinghouse Electric Corporation,"East Pittsburgh, Pa, a corporation of Pennsylvania Application September so, 1949, Serial No. 118,885

This invention relates to aviation gas turbine power plants of the type equipped with thrust destroyer'or variable area exhaust apparatus, and has for an object the provision of an improved variable area nozzle apparatus for a turbojet having an afterburner.

It has been proposed to equip the exhaust noz'zle'of a turbojet engine with suitably operabl'e'shutterelementsdesigned to eifect variations in the flow'area of thenozzle opening. Since theexha'ust end of such an engine tends to become quite hot, particularly when the power plant includesafterburner or thrust augmentor apparatus for burning additional fuel downstream of the usual turbine which drives the compressor of the engine, it is desirable to devise means for ensuring adequate cooling of the nozzlecomponents for avoiding undue thermal expansion and consequent structural strains on the apparatus. Accordingly, another object of the invention is the provision ofimproved variable'area nozzle apparatus constructed and arranged'to effect circulation of air over suitable areas of'the surfaces most likely to be subjected t'o'excessive heat during operation of the afterburnerapparatus, without unduly burdening the power plant" with bulky or complicated details of construction.

A feature of the invention is the provision of freely expansible baflie means for diverting cooling air over the desired areas of the movable exhaust nozzleelements when the latter are retracted to provide a fully open orifice or partially opened orifice, as is normally the case during operation of 1 the afterburner apparatus.

These and other objects are: effected by my invention aswill be apparent fromv the following description and claim taken in connection with theaccompanying drawing, forming a part Of'thlS. application, in which:

Fig: ,l'is' a-schematicelevationail View of a typicallaviation-turbojet power plant having'an afterburner'and variable area nozzle apparatus constructed in accordance with the invention;

Fig. 2is an enlarged detail sectional View of th'e nozzleapparatus shown in Fig. 1; and

Fig. 3 is a fragmentary enlarged detail sectional view of bne ofthe securing bolt arrangementssof the apparatusshown in Fig. 2.

As shownlzin Fig. 1 ofthedrawing, the power plant may comprise a turbojet engine It and a tailburner apparatus ll, both of which have substantially cylindrical casing structures mounted in coaxial alingment and adapted to be supported in the fuselage or wing of an aircraft 1 Claim. (Cl. Gil -35.6)

2 I (not shown). The turbojet engine It includes anouter casing IZ and an inner core structure generally indicated at l3; which form an annalar" passageway l4 extending" longitudinally through the engine from a forwardly directed air intake opening I5 to a re arwardly disposed turbine discharge passage 16. operating elements or the turbdjet engine'- are mounted iii axial alignment to minimize frontal area, and include an axial-flow compressor [1, an annular combustionapparatus [8, and a turbine [9, the rotor ofjwhich isoperatively connected to the rotor of the compressor through the medium o'f a common shaft 22' that is suitably journale'd within thecore structure [3. In operation} "air entering the intake opening I5" is compressed by thecompressor and delivered to the campus: tiori apparatus" [8, where fuel supplied by way of nozzles 2'4 is buri1ed'to form not motive fluid, which is' expan'd'ed through the turbine I9- for drivingthe compressor I1, and thence supplied through the discharge passage lli i'nto the after burner apparatus" H.

The afterburner apparatus III may'include' a generally cylindrical outer casing 26} the forward'endof which is suitably secured to the turbine discharge end of the engine casing structure [2. Formed in the casing 26 is anauxiliary'co'mbustion chamber 28; which communicates the aforesaid turbine discharge passage l6 and terminates in a jet dischargeopening o'r nozzle 29, the-flowarea of whichisvariable in accord ance" with thepositioning of" movable-lid" or 013.11 sure members aflan'd 31, hereinafter more fully described. Auxiliary fuel supply nozzles 32are mounted in the 'combustionchamberf28 for feed ingfuel into the path ofithe'heat'ed air and'gases flowing from the turbine" discharge" passage [6;

An aperturedbaffle or flame holder 33 may also be carried in: the combustion chamber 28: downstre'amo'f the nozzles 32. It will beundersto'o'd that, when it is desired to operate theiafte'rbuine'r' apparatus; fuel willbeautomatically' supplied by way; ofthe nozzlesfizj to be'burned in the chain? ber 23 toprovide additional thrust energy upon final discharge of the. heated motive fluid to atmosphere thrbughf the nozzle.- 29. "At the same timatne'HamembefS cianaai' win be retracted to their fully. open position, substantially a's'illus tratedilinthedrawing f. Referring to Fig. 2; it will be not'edthat the downstream portion 26a of the cylindrical afterburner casing 25 converges somewhat and terminates in an annular inwardly curved lip 26!),-

which defines the nozzle opening 29. For supextends through apertures formed in the ring 35,

shell 34 and in a bracket 39 carried by the casing 26, preferably with sufiicient freedom or lost motion engagement to permit differential thermal expansion of the associated casing sections.

A generally cylindrical baflle 40 having an outwardly flaring annular flexible flange 4| is mounted on the converging portion 26a of the afterburner casing, with the flange 4| directed upstream for supporting engagement with the adjacent inner surface of the shell 34 at a point remote from the bolt assemblies 36. The baflle 40 is carried on a number of circumferentially spaced bolt assemblies 43, and is held in spaced relation between the inner casing portion 26a and the outer shell 34 to form a continuation of the annular passage 31. As best shown in Fig. 3, each of the bolt assemblies 43 comprises a bolt 45 and sleeve 46 received thereon and fitted through an opening in the baflle 43, the shank of the bolt projecting inwardly through an opening in a bracket 41 which is welded to the shell portion 26a and clamped between the sleeve and a nut 48 applied to the end of the bolt. This arrangement is devised to permit differential expansion of the casing portion 26a and the baffle member 40, when subjected to heat incident to operation of the afterburner apparatus. Preferably, the inclined flange 4| is adapted to be spaced slightly from the shell 34 when the apparatus is cool, and to expand into engagement with the shell, as shown, during operation in a heated condition.

The nozzle closure members 30 and 3| are preferably arcuate in form, and have overlapped lateral lug portions 49 pivotally connected to the shell 34 by means of coaxial hinge pins 50, so that the members can be moved inwardly or toward each other to reduce the flow area of the nozzle 29, or outwardly toward the retracted position shown. The inner surfaces of the respective closure members are carried in sliding engagement on suitably curved sealing elements 5|, preferably formed of braded wire or other heat resistant material, which are in turn secured to a substantially annular flange 52 welded to the casing adjacent the lip 26!). Any desired actuating means (not shown) may be provided for operating the closure members 30 and 3| through the medium of movable linkage 53 connected thereto.

During operation of the afterburner apparatus with the lid members 30 and 3| retracted, as shown in Fig. 2, to render available the maximum flow area of the nozzle 29, atmospheric air will be caused to flow into the forward annular opening 34a and through the passage 34 for dissipating heat from the afterburner casing 26. The cooling air is then diverted, in the region of the seal flange 52, to flow as indicated by the arrows in Fig. 2 around the forward or pivoted portions of the lid members 30 and 3|, and finally passes rearwardly between the outer surfaces of the lid members and shell 34 to the exhaust opening 341). The seal element 5| at the same time prevents backflow of any hot engine exhaust gases issuing from the jet nozzle 29.

It will thus be seen that, with the relatively simple and light-weight construction and arrangement of the elements of the improved variable area nozzle apparatus embodying the invention, full length cooling of the inner casing and all movable parts is ensured, without necessitating any material extension of the overall dimensions of the power plant.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What I claim is:

Variable exhaust nozzle apparatus for a jet engine comprising a substantially cylindrical inner casing terminating in a nozzle opening for engine exhaust gases, a larger substantially cylindrical outer casing surrounding said inner casing, a plurality of circumferentially spaced radially disposed bolt assemblies secured to one of said casings and slidably retained in apertures formed in the other casing for holding said outer casing in differentially expansible spaced relation on said inner casing, said casings being concentrically arranged to form an annular cooling passage having a forwardly directed air inlet and an air outlet disposed near said nozzle opening a plurality of movable closure elements operatively mounted on said outer casing for varying the flow area of said nozzle opening, said closure elements being retractible into said cooling passage, a sealing flange carried by said inner casing in sealing engagement with said closure elements for cutting off communication from said nozzle opening to said cooling passage, and an annular baflle flexibly mounted between said casings upstream of said sealing flange, the upstream end of said baflle being engageable with the outer casing and its downstream end being spaced between said inner casing and said closure elements for directing cooling air from said passage into heat exchange relation with heated surfaces of the apparatus.

CHARLES R. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,572,812 Rees Feb. 9, 1926 2,408,099 Sherman Sept. 24, 1946 2,455,385 Schairer Dec. 7, 1948 2,477,683 Birmann Aug. 2, 1949 2,479,776 Price Aug. 23, 1949 2,481,330 Neal Sept. 6,,1949 2,516,910 Redding Aug. 1, 1950 2,523,842 Oulianoff Sept. 26, 1950 FOREIGN PATENTS Number Country Date Great Britain Apr. 29, 1947 

